Class: DatumLoader

const filter = new DatumFilter();
filter.nodeId = 123;
// configure other filter settings here...

const urlHelper = new NodeDatumUrlHelper();

new DatumLoader(urlHelper, filter).load((error, results) => {
  // results is an array of Datum objects
});

Extends

• JsonClientSupport

Members

---

<static, readonly> version :string

The class version.

Type:

• string

---

<protected> authBuilder :AuthorizationV2Builder

An authorization builder to use to make authenticated HTTP requests.

Type:

• AuthorizationV2Builder

Inherited From:

• JsonClientSupport#authBuilder

---

filter :DatumFilter

Type:

• DatumFilter

---

urlHelper :NodeDatumUrlHelper

Type:

• NodeDatumUrlHelper

Methods

---

callback( [value])

Get or set the callback function, invoked after all data has been loaded. The callback function will be passed two arguments: an error and the results. In incremental mode, the callback will also be passed a boolean that will be true on that last page of data, and a Pagination that details which page the callback represents.

Parameters:

Name	Type	Argument	Description
value	DatumLoader~dataCallback	<optional>	the callback function to use

Returns:

when used as a getter, the current callback function, otherwise this object

Type

DatumLoader~dataCallback | DatumLoader

---

client( [value])

Get or set a JSON HTTP client function to use.

The function must be compatible with d3.json and defaults to that. This provides a way to integrate a different HTTP client if needed, for example a mock implementation in tests.

Parameters:

Name	Type	Argument	Description
value	function	<optional>	the JSON client function, compatible with d3.json

Inherited From:

• JsonClientSupport#client

Returns:

when used as a getter, the JSON client function, otherwise this object

Type

function | DatumSourceFinder

---

concurrency( [value])

Get or set the concurrency limit to use for parallel requests.

By default requests are not made in parallel (this property is configured as 0). Change to a positive number to enable parallel query mode.

When parallel mode is enabled the loader will make one request that includes the total result count and first page of results, followed by parallel requests for any remaining pages based on that total result count and configured page size.

Parameters:

Name	Type	Argument	Description
value	number	<optional>	the concurrency level to use, or Infinity for no limit

Since:

• 1.1.0

Returns:

when used as a getter, the current concurrency value, otherwise this object

Type

number | DatumLoader

---

fetch()

Asynchronously load the data.

This method calls JsonClientSupport#load to perform the actual work.

Inherited From:

• JsonClientSupport#fetch

Returns:

the result promise

Type

Promise.<*>

---

includeTotalResultsCount( [value])

Get or set the flag for requesting the total results count.

By default the datum loader will not request the overal total result count when querying for data, as this speeds up queries. By setting this to true the total result count will be requested on the first query page.

Parameters:

Name	Type	Argument	Description
value	boolean	<optional>	the flag to include total results count

Returns:

when used a a getter, the total results count inclusion mode; otherwise this object

Type

boolean | DatumLoader

---

incremental( [value])

Get or set incremental mode for loading the data.

When incremental mode is enabled (set to true) then the callback function will be invoked for each result page that is loaded. The function will be passed a second boolean argument that will be set to true only on the last page of result data, and a third Pagination` object argument that details the starting offset of the page.

When incremental mode is disabled (set to false, the default) then all result pages are combined into a single array and the callback will be invoked just once.

Parameters:

Name	Type	Argument	Description
value	boolean	<optional>	the incremental mode to set

Returns:

when used a a getter, the incremental mode; otherwise this object

Type

boolean | DatumLoader

---

load( [callback])

Initiate loading the data.

As an alternative to configuring the callback function via the DatumLoader#callback method,a callback function can be passed as an argument to this function. That allows this function to be passed to things like queue.defer, for example.

Parameters:

Name	Type	Argument	Description
callback	DatumLoader~dataCallback	<optional>	a callback function to use; either this argument must be provided or the function must have already been configured via DatumLoader#callback

Overrides:

• JsonClientSupport#load

Implements:

• Loader#load

Returns:

this object

Type

DatumLoader

---

paginationSize( [value])

Get or set the result pagination size.

Parameters:

Name	Type	Argument	Description
value	number	<optional>	the pagination size to set; defaults to 1000

Returns:

when used as a getter, the pagination size; otherwise this object

Type

number | DatumLoader

---

parameters( [value])

Get or set additional URL parameters. The parameters are set as object properties. If a property value is an array, multiple parameters for that property will be added.

Parameters:

Name	Type	Argument	Description
value	object	<optional>	the URL parameters to include with the JSON request

Returns:

when used as a getter, the URL parameters, otherwise this object

Type

object | DatumLoader

---

readings( [value])

Get or set readings mode for loading the data.

When readings mode is enabled (set to true) then the /datum/reading endpoint will be invoked to load data.

When readings mode is disabled (set to false, the default) then the /datum/list endpoint will be invoked to load data.

Parameters:

Name	Type	Argument	Description
value	boolean	<optional>	the readings mode to set

Returns:

when used a a getter, the readings mode; otherwise this object

Type

boolean | DatumLoader

Type Definitions

---

dataCallback( [error], data [, done] [, page])

The data callback function.

Parameters:

Name	Type	Argument	Description
error	Error	<optional>	an error if a failure occurred
data	Array.<Datum>		the result data
done	boolean	<optional>	in incremental mode, will be true when invoked on the last page of data
page	Pagination	<optional>	in incremental mode, the page associated with the data